Struggling to change down on front derailleur

[Rohloff_Brompton_Rider]

I was thinking similar, but the assembly would be under tension in the big ring (we assume) I'd suspect an errant item - stone etc. Stuck in the parallelogram mech somewhere? There's lots of debris around from the rain...

there is a lot of cable pulled on the front mech. the only reason i said this, is it happens on my brompton every fold because i cable tied the dynamo wires in the wrong place and too lazy to sort it.

but like you said it could just be shoot in the mech.

 

[betty swollocks]

Are the two plates of the derailleur parallel to the chainrings? Maybe it's swivelled around the seat tube a bit?
Just a thought.

 

[Mad at urage]

I've had my road bike (first bike in nearly twenty years!) for a couple of weeks but on the last two rides I've had problems changing down on the front derailleur, every time I try to it just gets stuck halfway with the chain rubbing on the derailleur but not moving down to the smaller cog. The only way I can get it to change is to stop, pick the back wheel up and turn the pedal by hand, when I do this it shifts fine but clearly this is not helpful when trying to get up a hill!

Can anyone point me in the direction of some instructions on how to fix this? If it makes any difference they are shimano 2300 3-ring front set.

TIA

Re. the bold: Have you started trying to change down under load? If so, you need to change to the inner ring somewhat earlier, whilst you are still spinning and not leaving it until you are having to keep a lot of power through the pedals.